Tile questions

[ENIGMAX]

    this might be a stupid question, but what % of a tileset
    can be changed before you can call it your own… ex.
    i like the zelda tiles because they are very clean, so lets'
    say that i took a "zelda tree" and i recolored and shaped
    it slightly and added some new slight design features,
    would i you be able call it my own, even thought it still
    sorta repersents a zelda tree in some form or other.